1,3,4-thiadiazine herbicides

ABSTRACT

New N-substituted derivatives of 2-amino-5-tert.butyl-6H-1,3,4thiadiazine are employed to combat undesired vegetation by both post- and pre-emergent application techniques, carbamyl substituted compounds are preferred.

United States Patent 1 Doyle, Jr.

1451 Jan. 21, 1975 [54] 1,3,4-THIADIAZINE HERBICIDES [75] Inventor:William C. Doyle, J12, Leawood,

Kans.

[73] Assignee: Gull Research & Development Company, Pittsburgh, Pa.

22 Filed: Apr. 25, 1974 211 Appl. No.: 464,282

Related U.S. Application Data [62] Division of Ser. No. 361,366, May 17,1973.

[52] U.S. Cl. 260/243 R, 71/90 [51] Int. Cl C07d 93/22 [58] Field ofSearch 260/243 R [56] References Cited UNITED STATES PATENTS 3,290,30312/1966 Trepanier 260/243 3,779,736 12/1973 Doyle 260/243 PrimaryExaminer-John M. Ford [57] ABSTRACT 5 Claims, N0 Drawings1,3,4-THIADIAZINE HERBICIDES This is a division of application Ser. No.361,366, filed May 17. 1973.

DESCRIPTION OF THE INVENTION structural formula S /R 11/ W n ((JHS)S(J\N/ in which R is hydrogen, methyl or ethyl and R is selected from thegroup consisting of lower N-alkyl or N- alkenyl carbamyl, lowerN-alkenyl or N-alkylthiocarba- 2 my], C to C acyl and loweralkoxycarbonyl substituents. The novel compounds may be prepared fromavailable starting materials according to procedures of the typespecifically exemplified below.

PROCEDURES FOR SYNTHESIS OF HERBICIDES Preparation of 2-Amino-5-tert.butyl-6H-1,3,4-thiadiazine A mixture of 25.4 g thiosemicarbazidehydrochloride and 35.6 g of 1-bromo-3,3-dimethyl-2-butanone in 100 ml ofabsolute ethanol is heated l5 to hours on the steam bath. The resultantslurry is filtered-and the solid is washed with ethanol, dissolved inwater and neutralized with sodium carbonate, giving 14.5 g of 2-amino-5-tert. butyl-6H-l,3,4-thiadiazine, m.p. 724.

Using the same procedure, the reaction of 4-methylthiosemicarbazidehydrochloride and 4-ethylthiosemicarbazide hydrochloride gives2-methylamino-5- tert.butyl-6H-l,3,4-thiadiazine and 2-ethylamino-5-tert.butyl-6H-1,3,4-thiadiazine respectively.

Preparation of N-methyl-N'-(5-tert.butyl-6H-1,3,4-thiadiazin-2- yl)ureaTo a solution of 8.0 g 2-amino-5-tert.buty1-6H-l ,3,4- thiadiazine in mldioxane is added rapidly 2.7 g methyl isocyanate, causing a slight risein temperature 10 and the gradual precipitation ofa crystalline solid.This solid .is collected by filtration and is washed with hexane, givingN-methyl-N-(5-tert.butyl-6H-1,3,4- thiadiazin-2-yl)urea, m.p. 1913. In asimilar manner the reaction of methyl isocyanate with the appropriate 52 -a1ky1aminothiadiazine gives N,N'-dimethyl-N'-(5-tert.butyl-6H-1,3,4-thiadiazin-2-yl)urea and N-methyl-,N'-ethyl-N'-(5-tert.butyl-6H-1,3,4-thiadiazin-2- yl )urea.

Preparation of 20 N,N-dimethyl-N-(5-tert.buty1-61-1-1,3,4-thiadiazin-2-yl)thiourea A solution of 21.5 g of Z-methylamino-5-tert.butyl- 6l-I- l,3,4-thiadiazine and 6.7 g methyl isothiocyanate in 5 50 ml dioxane isheated to reflux for several hours and the solution is evaporated todryness on a rotary evaporator. The residue is dissolved in benzene andthe benzene solution is extracted with water, dried and evaporatedgiving N,N'-dimethyl'N'-(5-tert.butyl-6H-1,3,4-

thiadiaZin-Z-yUthiourea as a viscous gum.

Preparation of 2-Chloroacetamido-5-tert.butyl-6H- l ,3 ,4-thiadiazine Toa solution of 3.7 g of 2-amino-5-tert.butyl-6H- 1,3,4-thiadiazine and2.2 g triethylamine in 25 ml dioxane is added dropwise 2.5 g ofchloroacetyl chloride. The solution is stirred several hours, pouredinto water and the resultant precipitate filtered, washed with water andair dried to give 2-chloroacetamido-5- tert.butyl-6H-l,3,4-thiadiazine,m.p. 158-9.

Using procedures similar to those described above, the remainingcompounds listed in Table l were prepared.

TABLE I N I N (CHa)aC-- N Analysis Gale (1 Found R R MJ. C.) C H N C H NH H 724 49. 09 7. 65 24. 54 CH3 H 83-4 51. 58 8. 12 22. 56 51. 74 8.1122. 78' CzH5 H 115-20 54. 23 8. 60 21. 08 54. 24 8. 62 21. H CONHCH1191-3 47. 40 7.02 24. 47. 83 7. 38 23. 23 CH: C0NHCH1 79-81 49. 56 7. 4923. 12 46. 58 7. 93 21. 14 C3H CONHCH3 108-110 51. 53 7. 86 21. 86

COCH;C1 158-9 43. 5. 66 16. 99 43. 48 5. 88 16.67 CH; --C0OCH3 011 49.36 7. 04 17. 27 50. 23 7. 16 15. 00 CH: -CO0CII2CII;CI 56-60 45. 28 6.22 14.40 45. 44 6. 40 14. 08 C113 -CSN] 1C 113 46. 48 7. 02 21. 68 47.02 7. 48 18.24 (111 C ()0 (3 1 1 71-4 55. 00 7. 47 14. 83 54. 06 8. 0415. 28 CH; -CO() (32115 -90 54. 74 7.113 17. 41 54.116 8. 06 16. 811 CH3C ()N] IAIlyl 119-20 53. 70 7. 51 20. 88 53. 54 7. 34 Z0. [16

1 Gum.

3 Combating Unwanted Vegetation E The novel herbicides are effectivewhen used both postand pre-emergently. There is described below anillustrative procedure for herbicidal use of the com- 5 pg pounds undercontrolled conditions in the greenhouse 5. so as to obtain data onphytotoxic activity and selectiv- E; ity.

B l. Post-Emergent Use An aqueous dispersion of each active compound wasa: prepared by combining 0.4 gram of the compound with 5 3 about 4 ml ofa solvent-emulsifier mixture (3 parts of a commercial polyoxyethylatedvegetable oil emulsig mwwagaagmflwcm, fier, one part xylene, one partkerosene) and thenadding water, with stirring, to a final volume of 40ml.

The species of plants on which each compound was I I I I I I to betested were planted in four-inch pots in a green- 5*" 5 5 5* 5 5 5house. Ten to eighteen days after emergence of the E E E E E E E Eplants, three pots of each species were sprayed with an E 5 5 5 Eaqueous dispersion ofthe active compound prepared as g 5" 3* 5" 5" 5 5 5described above, at a rate of 5 lb of active compound 0 E E 5 E per acreand at a spray volume of 60 gallons per acre. l i i f 1 Approximatelyone week after the spray application g E"' the plants were observed andthe results rated accord- O E ing to the following schedule. E

a KOQQQQH QQQ' M :HN E a a Y i DEGREE OF EFFECT m 65 g E E E E" E E E Es z z 0 no effect 2 (S E E E l l slight effect a )=Z\ i l E i i E l2=moderate effect E u: 2 ix lqi l u id! lo l l l.-. 3 severe effect m 5l l i l 1 l i I 4 maximum effect a 3 E E i E i E E E (all plants died) 5g I 7 l E E1 5 i i E i E i o l t 1 l V oawnsflr-twv-twfl-m-toow The samerating schedule was employed to judge pre- H N N :d :c :0 :H emergentresults obtained according to the procedure a 5 5 5 g 5 5 3 below. g l ll E E l 5 a E, Ev Ea Ea Em EH 5 E s s s s a a a 2. Pre-Emergent Use g El l i E i E U 1 1 i A solution of each active compound was prepared by EE 5 E E E E dissolving 290 mg of the compound to be tested in 200 5 E EE E E E E N m I l l I 1 ml of acetone. Disposable expanded polystyrenetrays 5 a, 5 5 5 5 5 5 l about 2 inches deep and about one square footin 5 i 5 E E E E area were prepared and sprayed with the acetone solu- EE E E E E E E E E E E E E tion at the rate of 10 lb of active chemicalper acre of E 5 5 5 5 sprayed area and were then covered with about one-E E E E E E E E E E E E E E fourth inch of soil. Twenty-one days afterseeding and a E E, E E E, E L} Li E 1 (I! I'll [I] I!) m U '0 treatmentthe plants were examined and herbicidal ef- Q 5 5 5 5 5 5 feet was ratedaccording to the above schedule. N Both post-emergent and pre-emergentresults are set g forth in the following table. II 0 H m o a s b1 u 9. Lb1 E! n 0 l I 1 0 o o :1: i=1 0 o m m 1:: 0 0 In It Z Z Z O O 2 2 o o oo o w o o o o o o o o m I I I I l l :5 E E1 E1 ii M I11 0 O

2. N-methyl-N''-(5-tert.butyl-6H-1,3,4-thiadiazin-2-yl)urea. 3.N-ethyl-N''-methyl-N-(5-tert.butyl-6H-1,3,4-thiadiazin-2-yl)urea. 4.Methyl N-(5-tert.butyl-6H-1,3,4-thiadiazin-2-yl)-N-methylcarbamate. 5.N-allyl-N''-(5-tert.butyl-6H-1,3,4-thiadiazin-2-yl)-N''-methylurea.